Tuesday in San Francisco at the Facebook development conference, Facebook CEO founder Mark Zuckerberg without naming him specifically, blasted Republican presidential candidate Donald Trump for his proposals to build a U.S.-Mexico border wall, and blocking ISIS from using the internet.

Zuckerberg said, “Now as I travel around the world I’m starting to see people and nations turning inward, against this idea of a connected world and a global community. I hear fearful voices calling for building walls and distancing people they label as others, for blocking free expression, for slowing immigration, reducing trade, and in some case even cutting access to the Internet.”

He added, “Instead of building walls we can help people build bridges, and instead of dividing people we can help bring people together.”